Create resizer for allocation perspective split view

Source/devtools/front_end/heapProfiler.css

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 96 matching lines @@
 
 .heap-snapshot-view .heap-tracking-overview {
     flex: 0 0 80px;
     height: 80px;
 }
 
 .heap-snapshot-view .retaining-paths-view {
     overflow: hidden;
 }
 
-.heap-snapshot-view .retainers-view-header {
+.heap-snapshot-view .heap-snapshot-view-resizer {
     background-image: url(Images/statusbarResizerVertical.png);
     background-color: rgb(236, 236, 236);
     border-bottom: 1px solid rgb(179, 179, 179);
     background-repeat: no-repeat;
     background-position: right center, center;
     flex: 0 0 21px;
 }
 
-.heap-snapshot-view .retainers-view-header .title > span {
+.heap-snapshot-view .heap-snapshot-view-resizer .title > span {
     display: inline-block;
     padding-top: 3px;
     vertical-align: middle;
     margin-left: 4px;
     margin-right: 8px;
 }
 
-.heap-snapshot-view .retainers-view-header * {
+.heap-snapshot-view .heap-snapshot-view-resizer * {
     pointer-events: none;
 }
 
 .heap-snapshot-view tr:not(.selected) td.object-column span.highlight {
     background-color: rgb(255, 255, 200);
 }
 
 .heap-snapshot-view td.object-column span.grayed {
     color: gray;
 }
@@ skipping 57 matching lines @@
 .heap-snapshot-stats-name,
 .heap-snapshot-stats-size {
     display: inline-block;
     margin-left: 6px;
 }
 
 .heap-snapshot-stats-size {
     float: right;
     text-align: right;
 }